1. Field of the Invention
The invention concerns an underground protective shelter, and in particular a shelter with a plurality of connected protective chambers, assembled of prefinished building components of steel-reinforced concrete, hermetically sealed at junctions, and braced by clamping components.
2. Description of the Prior Art
A protective bunker installation is disclosed in Offenlegungsschrift No. 21 60 570 having individual protective chambers in the shape of parabaloids, spheres, or other shapes which may be described by rotating curves. The chambers are connected to one another on their narrow, continuously-curved side surfaces by means of longitudinal, tubular-shaped connector tunnels. Each individual protective chamber is assembled of several prefinished and preferably sector-shaped steel-reinforced concrete components. Connection takes place along horizontal or vertical expansion joints and is intended to be humidity- and gas-tight.
Auslegesschrift No. 12 64 737 teaches an underground protective shelter installation having an entry passageway and access to a neighboring building. It additionally discloses an emergency exit, and has a passageway that and makes it possible to exit to open areas above ground.
Auslegesschrift No. 12 62 006 discloses an underground protective shelter installation of prefinished concrete components. The individual prefinished concrete components are connected with screws and suitable shearing inserts so that they are safeguarded against shearing and are gas- and moisture-tight.
Finally, Auslegesschrift No. 11 43 627 concerns an underground protective bunker installation of prefinished cement components with several connected protective chambers, wherein all the protective chambers are hollow spheres, the spheres being connected with one another by an intersecting seal across two opposite round openings of the same size.
Before the development and testing of the atomic bomb, conventional protective shelter installations consisted typically of very thick ceilings of steel and concrete, which were intended to mainly protect against the effect of explosions due to conventional bombs or artillery shells.
Such protective shelters were designed for protection against more or less direct hits and also for protection against the shrapnel and parts flying through the air in the vicinity of a bomb explosion. Protection against gas attack was primarily accomplished by individual protective equipment such as gas masks. The protective bunker installation in these times was used practically only during actual attack and could be safely left immediately after the attack.
Protective shelter installations formerly known and a few of the above mentioned ones, closely follow the construction principles valid at that time. For example, in Offenlegungsschrift No. 21 60 570, a heavy additional upper layer of cement is suggested, in order to protect against direct hits. The individual protective chambers of known protective shelter installations, however, are constructed most unappealingly and are suitable only for a short stay in the protective chamber itself. The design of known inner chambers give the visitor the impression that he is in protective custody. The chambers are strongly constructed, but are in no way comfortable or pleasing to the eye.
In modern times, civil defense protection against more or less direct hits from explosives projectiles has moved into the background compared to protection against atomic, bacteriological and chemical warfare. Today's protective bunker installations must be constructed to be sufficiently safe against these modern methods of warfare. In keeping with the nature of the expected lingering hazards, relatively long periods of stay in the bunker must be planned. These methods of warfare cause a much longer after-effect than former methods. The effects must be allowed to fade to levels nontoxic for humans before the shelter can be safely abandoned. For example, after the use of atomic weapons, a short period of initial radiation is expected, but thereafter residual radiation will remain, and fallout including radioactive rain.
After the use of bacteriological and chemical weapons, the environment may possibly be contaminated for an even longer period of time than that caused by the use of atomic warfare. The effects of such weapons force a minimum protective stay of several weeks, and preferably a longer period of stay in the protective bunker. Therefore the bunker must afford sufficient comfort and be designed for sufficient safety so that such long periods of time can be endured. Furthermore a protective bunker installation must satisfy the needs of the protected occupants insofar as possible and to afford them the capability of observing and exploring the immediate surroundings during the period the atomic, bacteriological, or chemical stress.